The disclosure relates generally to integrated circuits (ICs), and more particularly to the field of connection of data transmission medium to integrated circuit packages and convective heat removal.
On today's printed circuit boards, information and electrical power is typically transferred over copper wires between CPUs, memory and I/O devices. Interconnect technologies such as pins, ball bonding and solder bumps connect the wires with the devices. While fiber optic links have so far dominated network and data communications for long distances, copper still generally prevails as the interconnect of choice at shorter distances, for reasons of cost, reliability, availability, and ease of manufacturability.
However, optical links receive more and more attention as copper interconnects are reaching their physical limits in terms of data rate requirements and density, at least in some applications. Thus, optical interconnects are today regarded as one solution to mitigate the communication bandwidth bottleneck as expected in future computing applications. Yet, the extension of optical interconnects to chip-scale systems has received limited attention only, due to difficulties in reliably integrating optoelectronic systems on this scale. Some solutions are proposed in the literature, see e.g., Prather et al., IEEE Photon. Technol. Lett., vol. 13, pp. 1112-1114, October 2001.
Typical solutions proposed in the literature consist, for example, of providing a chip stack with heat removal from one side through some convenient thermal interface and an optical back plane on the opposite side of the chip stack. Such a configuration has a number of drawbacks. Notably, electrical Input/Output (I/O) and power delivery have to share a chip face area with optical I/O, which constrains the power delivery. This further assumes integrating optical and electrical technologies into a same board, which results in processing constraints and routing congestions. Furthermore, the temperature sensible optical element (in this case a laser), is placed in close vicinity of a CMOS chip, which is typically operated at high temperatures.
The following documents discuss aspects of the background art. Useful technical details may be found therein:
“Fluid optical waveguides for on-chip manipulation and generation of light”, Vezenov, D. V., Mayers, B. M., Tang, S. K. Y., Conroy, R. S., Wolfe, D. B., Whitesides, G. M., IEEE Conference Proceedings, LEOS Summer Topical Meetings, 2006, Digest. This paper discusses applications of liquid-core liquid-cladding waveguides in several dynamic photonic systems. These optical components could be reconfigured in terms of their geometry, refractive index, or chemical composition.
“Liquid core modal interferometer integrated with silica waveguides”, Dumais, P. Callender C. L., Noad C. J., Ledderhof C. J., IEEE photonics technology letters, 2006, vol. 18, no 5-8, pp. 746-748, wherein an integrated structure is demonstrated as a refractive index sensor. The structure consists of a liquid-filled elliptical microchannel embedded in silica glass and integrated with waveguides.
U.S. Pat. No. 5,394,490, wherein a clock signal supply system is disclosed for a semiconductor device with a semiconductor chip and a wiring substrate connected in flip-chip fashion and an optical waveguide interposed in the space between electrode members, in which the mutual arrangement of the electrical interconnection and the optical waveguide interconnection on the wiring substrate is not affected and can be used separately from each other for different applications, thereby improving the throughput of the interconnections as a whole.
U.S. Pat. No. 5,761,350, wherein improved Micro OptoElectroMechanical Systems (MOEMS) are provided to support the seamless integration of high performance computer systems and communication networks. Such MOEMS integrate high speed electronic processing units and high bandwidth photonic interconnection networks by combining them into a single module: (1) active electronic/photonic processing units, (2) passive electronic/photonic interconnection networks, and (3) micromachined silicon mirrors used as optical Input/Output (I/O) couplers.